GOOD: Feed your fountain pen a steady diet of fountain pen ink. Period. This injunction may seem obvious, but it is not quite so obvious as it appears. Fountain pen ink is a solution. To the chemist, a solution consists of a fluid in which other substances are dissolved (the solvent), and the dissolved substances (the solutes). The solutes are actually reduced to the molecular level, the same as the solvent, and all the different molecules are mixed up evenly to create a uniform fluid, a pure liquid[1] that contains no microscopic particles of solid material. The solvent in fountain pen ink is distilled water, and the solutes are dyes, wetting agents, and mold inhibitors. Because it’s a solution, fountain pen ink contains no solid matter at all. This is an important point to remember.